1419315 - scroll thumb/arrow button disappears sometimes

Status: RESOLVED WORKSFORME

(Core :: Web Painting, defect, P2)

Description

[Alice0775 White]

Attachment: about:support

Reproducible: always

Steps to reproduce:
1. Open https://news.google.com/news/headlines?ned=us&hl=en&gl=US , no need login
2. mouse hover over scroll thumb
  ---- scroll thumb will disappear at first time sometimes
3. drag thumb to upperwords
  ---- scroll thumb will disappear
4. mouse release when mouse pointer on the upper header pane
  ---- reappear
4. move mouse to arrow button and thumb
  ---- scroll arrow button and thumb will disappear

Actual Results:
scroll thumb/arrow button disappears sometimes


Regression window:
https://hg.mozilla.org/integration/mozilla-inbound/pushloghtml?fromchange=7fb001f811d183095e9cfdd958c9215484377396&tochange=d5e1ed773fefe2eb9d52402dd74b5fea19b8b4a4

Comment 1

[Andrew Overholt [:overholt]]

Matt, do you know what caused this? FWIW I can't reproduce (or I'm mis-interpreting).

Comment 2

[Alice0775 White]

Attachment: screencast

Still reproduce on 59.0a1 (2017-11-29).

Steps to reproduce:
1. Open https://news.google.com/news/headlines?ned=us&hl=en&gl=US , no need login
2. mouse hover over scroll thumb
3. drag thumb to upward
  ---- scroll thumb will disappear
4. mouse release when mouse pointer on the upper header pane
  ---- reappear
4. move mouse to arrow button and the thumb
  ---- scroll arrow button and thumb will disappear

Comment 3

[Matt Woodrow (:mattwoodrow)]

Thanks Alice, I can reproduce this on my Windows machine.

Will look into it tomorrow.

Comment 4

[Alice0775 White]

I cannot reproduce the problem after the site layout has changed slightly.